1. Field of the Invention
The present invention relates to an inner surface measuring apparatus.
This application is based on Japanese Patent Application No. 2005-218654, the content of which is incorporated herein by reference.
2. Description of Related Art
Conventionally, a surface state meter having a contacting probe is known as an apparatus for measuring surface information of a measurement object, such as surface roughness and contour shape, (for example, Mitutoyo Corporation, Product Information, Searched on 31 May 2005, Internet <URL: http://www.mitutoyo.co.jp/products/keijyou_hyomen/hyomen—01.ht ml>).
This surface state meter measures a contour shape and so forth of a measurement object by making a contacting probe contact with the surface of the measurement object and relatively moving the contacting probe. Specifically, this surface state meter measures the contour shape and so forth of the measurement object by detecting an amount of movement of the contacting probe along the surface shape of the measurement object.
However, there are limits in measuring surface shape using the contacting probe. For example, in the case of measuring the inner surface shape of a hole where a sectional area of the hole is comparatively large and an inside diameter of the hole is unlikely to change in the depth direction of the hole, it is possible to measure by making a small probe contact with the inner surface. However, in the case where the sectional area of the hole is comparatively small and the inside diameter is small at the entry of the hole and becomes greater further away from the entry in the depth direction, there is a disadvantage in that a small probe that can pass through the entry cannot make contact with the inner surface at the deeper end of the hole, making measuring difficult.